Field of Invention
The invention relates to a centrifugal fan and, in particular, to a fan frame.
Related Art
With the higher and higher demand for the heat dissipation of systems, more and more fans with different sizes are developed and utilized. No matter what kind of size or type the fan is, increasing the heat dissipation efficiency is a main trend in the current industry.
FIG. 1A is a schematic diagram of a conventional fan. As shown in FIG. 1A, the fan F′ includes a fan assembly 1 and a fan frame 2. The fan frame 2 is disposed corresponding to the fan assembly 1. The fan frame 2 is disposed around the fan assembly 1 and an accommodating space S′ is formed therebetween. The fan frame 2 further includes an inlet structure 21 at the inlet of the fan. When the fan assembly 1 is operated, a flow field is formed within the accommodating space S′, and the outside air will enter into the flow field through the inlet structure 21. Accordingly, the heat dissipation efficiency of the fan F′ can be improved by changing the shape of the inlet structure 21.
FIG. 1B is a schematic sectional diagram of the inlet structure taken along the line A-A in FIG. 1A, and FIG. 1C is a schematic diagram of another view of the inlet structure in FIG. 1A. As shown in FIGS. 1B and 1C, the inlet structure generally includes a hollow portion 221 having an chamfering angle r′. The hollow portion has a circular shape. In the conventional art, the shape of the inlet structure can be adjusted to increase the heat dissipation efficiency of the fan. For an example in FIG. 1D, the inner edge of the hollow portion 221a is shaped with a plurality of first chamfering angles R′, and thus the hollow portion 221a is changed into a non-circular shape. Therefore, the heat dissipation efficiency will be increased. However, the extent of the increment of the heat dissipation efficiency is still limited just by reshaping the inner edge of the hollow portion 221a of the inlet structure 21 with a plurality of the first chamfering angles R′.
Therefore, it is an important subject to provide a fan and a fan frame thereof that can enhance the airflow entering into the flow field of the fan and smooth the flow filed much more so that the efficiency and property of the fan can be improved.